Band presses shown, for instance, in U.S. Pat. No. 3,071,032. In this known embodiment of a band press, the press plates of one plane are connected with one another and with the outer press plates through a press plate adjusting means of the lazy-tong type, so that, on separation of the outer press plates, those provided between them are each traveling a path that is proportional to their median distance from the plane of symmetry of the band press. This positive guidance of the press ledges is, however, delicate and sensitive and the functional reliability can, therefore, be impaired under the conditions of grime and abrasion prevailing in the rough rolling mill operation.
For this reason, another type of band press has been proposed, as shown in DT-OS 21 12 753, in which the worm-gear spindles have threaded sections in the number of the border plates or press plates, respectively, that are to be moved within the press surface, and in which the border or press plates are equipped with spindle nuts that engage the threaded sections. The thread pitches on this known embodiment are proportional to the main distances of the associated border plates or press plates from the plane of symmetry, and the over-all diameters of the thread sections drop from the inside to the outside at least to the value of the pitch diameter of each preceding thread section; the known worm-gear spindles are connected via a vertical shaft through bevel gearings of which at least one bevel gear is able to slide axially on the vertical shaft by means of a multiple spline connection.
This known band press has the disadvantage that it requires the adjustment of the press plates within both planes to positively identical widths, whereby the press plates must participate in the movement in a manner always proportional to their mean distance from the plane of symmetry of the band press. This requires the installation of rather expensive worm-gear spindles with threads of variable pitch, which, on the one hand, are fairly costly to manufacture and, on the other hand, also require regular maintenance.
This is an object of the present invention to eliminate the disadvantages of the known embodiments of band presses and to create a band press of the initially mentioned kind that can be manufactured relatively simple, as well as in an economical manner, and which is, nevertheless, of rugged construction and, therefore, satisfactorily functionable in the rough rolling mill operation without expensive maintenance.